Route 66 Road Trip Guide 4+

Much improved since the recent update.

There wasn't much description of this app when I downloaded it, but for $3 I took a chance.
The app has profiles of about 100 points of interest along Rte. 66 in 8 states: IL, MO, KS, OK, TX, NM, AZ and CA. Each includes a photo and a description (most of the ones I checked are copied verbatim from Wikipedia, with the source cited). There is also a link to the website for the place and a link to GPS. However, the GPS is standard, it won't follow Rte. 66 if there's a faster way via the interstate, which is what I was looking for in an app.
There is also an interactive map that has a line tracing Route 66 with flags that open photos of the places of interest covered in the app. You can zoom in and out and turn the map. However, the road names along Route 66 change, particularly in large towns and cities. Not only is there no information on these name changes, the line on the map often obscures these alternate names and I think it would be difficult to use on a smartphone screen, especially while driving.
As a reference and overview of notable sites along Route 66, this app might be worthwhile at this price point. But If you're planning a Route 66 trip, I'd recommend spending a bit more and buying the guidebook published by Moon, "Route 66 Road Trip" by Candace Taylor. It includes a lot more sites, maps, and step-by-step directions on following the Route 66.

Took me right to what I wanted to see. The navigation feature works great and makes it easy to get where you want to go.